Patent GB-881910-A (GB)
Title: Improvements in or relating to statistical record reading devices
Inventor: SMITH KENNETH LESLIE
IPC: G06K7/016
Filed: 1958-10-22
Abstract: 881,910. Reading record cards. INTERNATIONAL COMPUTERS & TABULATORS Ltd. Sept. 4, 1959 [Aug. 22, 1958], No. 33866/58. Class 106 (1). Timing pulses for reading out data sensed column-by-column from a record card are produced by a counter 17, Fig. 2, fed by clock pulses on line 15 which are related to the card feed, the counter being started by the appearance of the leading edge of the card under the sensing means and producing timing pulses in each column period. The card is sensed by a row of photocells P1-P9, PO, PB, PA, which receive light from a source 3 through the card perforations. Clock pulses are generated by a disc 8 rotating with the card feed rollers 1, peripheral holes 10 being sensed by a photo-cell 7. The pulses are amplified and inverted and applied to a trigger 14 which produces squared pulses CP, ICP, Fig. 3, on leads 16, 15. Pulses ICP are applied to counter 17 which consists of three trigger stages counting up to eight. Outputs are taken on lines 26 and 27 corresponding to counts of two and three. These pulses are shown at CP3 and CP4, Fig. 3, occurring in each column period of eight clock pulses. Lines 26 and 27 are connected to triggers 28 and 30 to produce control pulses C03, CO4, Fig. 3, on leads 29 and 31. One of these leads 29 is used to gate out the signals from the photo-cells P1-P9 where they emerge from amplifier 4. The other lead 31 gates out signals from the remaining photo-cells PO-PA and these therefore occur later by one eighth of a column period. The pulses CO3 and CO4 on leads 29 and 31 are also applied to a shift register having as many pairs of output leads 33 as there are columns. These leads become energized in turn, the two leads for each column being energized in quick succession. The data sensed is entered into a matrix store 49 (e.g. of magnetic cores) by the coincidence of signals on leads 33 and gated signals on leads L1-L9 and LO-LA. The data in the 1-9 zone of the card is entered first and followed, one eighth of a column period later, by the data in the O-A zone. If it is unnecessary to read out the two zones at different times, there may be only one lead from the counter 17 and only one lead 33 for each column. Operation.-As the card passes under the row of photo-cells light is cut off and the signal changes on all leads L1-L9 &c. Leads LO and LA are connected through a gate 35 and an inverter 37 to a " card-present " trigger 39 which is set thereby. Also the pulse from inverter 37 is delayed and applied to the first stage of the shift register where it enters a marker signal. This marker is moved along the register in synchronism with the movement of the card. The " card-present " trigger produces, at time Tl, Fig. 3, a setting pulse which is applied to zeroize and start the counter so that counting takes place in repeated cycles of eight clock pulses. The first two cycles correspond to the blank leading edge of the card there being no leads 33 from the corresponding shift register stages. At time T3 the first column sensing period SP1 begins, the holes in the first column being sensed shortly after the beginning of this period and the two zones of the card being read out and entered into the store at times T4 and. T5 by counter pulses CO3 and CO4 The following cycles are similar. When the marker pulse comes to the last stage of the register a signal is produced on lead 34 which resets the " cardpresent " trigger and stops the counter. Specification 881,909 is referred to.